Rotary Vane Vacuum Pump for RH Furnace
In industrial steel making production, the vacuum pumping equipment often used now mainly include roots vacuum pump, water ring vacuum pump, rotary vane vacuum pump and steam jet pump, among which rotary vane vacuum pump and steam jet pump are the most common used pumps.
Various vacuum refining technologies began to appear, such as vacuum ingot casting method, ladle trickle degassing method, ladle degassing method, etc., thus creating an industrial-scale vacuum treatment method for molten steel, especially the emergence of rotary vane vacuum pump, which is even more important. It accelerated the development of vacuum steel making technology.
This article mainly describes the application of rotary vane vacuum pump in RH furnace.
The vacuum pump is one of the necessary equipment for RH refining equipment. Its pumping capacity, pumping rate and other parameters directly affect the normal operation and metallurgical effect of RH furnace.
RH furnace system equipment is a secondary refining process equipment for molten steel used to produce high-quality steel. The whole metallurgical reaction of molten steel is carried out in a vacuum tank with a refractory lining. The lower part of the vacuum tank is two impregnated pipes with refractory lining, and the upper part is equipped with hot bending pipes. The pumped gas is discharged to the outside of the workshop from the hot elbow through the gas cooler to the vacuum pump system.
Before the molten steel treatment, the dip tube is first immersed in the molten steel of the ladle to be treated. When the vacuum tank is evacuated, the atmospheric pressure on the surface of the molten steel forces the molten steel to flow from the dip tube into the vacuum tank (about 0.67mbar in the vacuum tank can make the molten steel rise to a height of 1.48m).
Two immersion pipes communicated with the vacuum tank, one is an ascending pipe and the other is a descending pipe. Because the rising pipe continuously blows argon into the molten steel, a higher static pressure difference is generated compared to the descending pipe without argon blowing, so that the molten steel enters from the rising pipe and flows to the descending pipe through the lower part of the vacuum tank, and the cycle is repeated.
In a vacuum state, argon, hydrogen, carbon monoxide and other gases flowing through the vacuum channel molten steel are pumped away during the molten steel circulation process. At the same time, the molten steel entering the vacuum tank also undergoes a series of metallurgical reactions, such as carbon-oxygen reaction, etc. Such a circular degassing refining makes the molten steel purified.
The molten steel treated with RH has obvious advantages: the alloy basically does not react with the slag, the alloy is directly added to the molten steel, and the yield is high. The molten steel can be quickly and evenly mixed, the alloy composition can be controlled within a narrow range, the gas content is low. It can also use the top gun to adjust the temperature of chemical heating to provide the continuous casting machine with molten steel with good fluidity, high purity and conforming to the casting temperature, so as to facilitate the continuous casting of multiple furnaces in continuous casting production.
The metallurgical effect of rotary vane vacuum pump used in RH can reach or be better than the same process index of multi-stage vapor jet pump vacuum system. The rotary vane vacuum pump uses electric energy as the driving energy, and its operation is not restricted by vapor pressure and temperature.
The vacuum pump can be started and stopped at any time according to the actual production situation, and the production is flexible. The rotary vane vacuum pump is applied to the RH furnace process, which improves the pumping capacity, decarburization capacity, dehydrogenation capacity and molten steel circulation rate of the RH furnace. The vacuum pump system has stable operation, energy saving and environmental protection, which greatly reduces the production cost of the RH process.
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